Looks like it's $500 - or at least that's what my electrical bill was at.
I've recently raised the target temperature to 76 degrees. We'll see how this changes things.
Near the end of winter my electrical bill had dropped from about $250 to $170. It ran at that level for several months - I'm hoping it can be attributed to the increased use of compact flourescents throughout the house.
If our average electrical bill is perhaps $200, this means our cooling bill about $300. Interesting.
One thing I've done to cool the house more efficiently is turn the ceiling fans on in common rooms. This should help circulate air better.